Proteus - Geology, shape, and catastrophic destruction

Least-squares fits to the two available limb profiles of Proteus yield a sphericity close to unity; the visual irregularity is due to a degree of surface roughness comparable to that of Hyperion and the smaller icy satellites. A network of streaks that can be interpreted as tectonic troughs cuts the surface of Proteus, and is organized concentrically around either one of the two nearly-coincident Proteus-Neptune of Pharos axes of symmetry. If the streaks are tectonic, they may be due to tidal stresses generated by a past change in Proteus' equilibrium orientation. The streaks may also be disruptive-stress fractures.